This invention relates to an enfolding sound barrier for abating the noise from vehicles traveling on roads including express highways or from electric cars traveling on railroads or from other sound sources, and particularly relates to the construction of an enfolding sound barrier which utilizes principles, such as multiple diffraction, interference of sound waves and containment of reflected sound in the main track.
It is universally known that transport facilities are important socially and economically and abundant with features, such as public welfare and usefulness. In consequence of the rapid advance of such transport facilities, however, the noise emanating from electric cars and vehicles has been posing a serious social problem. Particularly, the seriousness of the problem of noise in the urban residential district has been growing in depth, and the problem of preventing noise pollution has been creating a profound public interest.
As measures for the prevention of the noise, it is conceivable to abate the noise from various transport facilities that are sources of noise or separate sources of noise, such as railroads and roads that are utilized by the transport facilities, from the residential district. These measures are invariably out of the ordinary. As a measure for realizing comparatively easy prevention of the noise, the practice of blocking the noise from the sound source by setting up a barrier, such as a soundproofing implement, has been in vogue. Thus, various soundproofing devices have been proposed.
For the purpose of reducing the noise emanating from electric cars and vehicles in motion traveling along transportation routes, for example, the sidewalls bordering on an express highway or a railroad are each provided on the upper part thereof with a device possessing a soundproofing property so that this device may be relied on to abate the sound. For the sake of increasing the soundproofing effect in this case, such means as forming the device wholly in a large size, enlarging the area of sound-absorbing material applied fast to the device, or imparting a complicated shape to the device are generally adopted to effect the absorption of the noise generated at the relevant site of noise abatement.
The railroad or the road which is provided with the soundproofing device necessitates a decrease in the height of the soundproofing device for the purpose of enabling the super-express train, elevated railroad train or vehicle to command the scene or the view of the surrounding district or reducing to the fullest possible extent the influence of the wind pressure exerted thereon. With a view to fulfilling this necessity, various means have been disclosed, such as a means of fixing sound-absorbing material along the upper edge of a given sidewall to thereby induce absorption of the sound waves tending to diffract to the reverse side of the sidewall, and a means of projecting a horizontal edge wall from the upper end of the sidewall toward the road, projecting from the leading terminal of this edge wall an upward directed wall rising vertically and an extended wall directed upward aslant toward the side opposite the railroad and further providing the projected walls each with a sound-absorbing material to thereby produce a soundproofing unit capable of absorbing the sound waves separated downward from the noise generated by the diffracting sound waves or the pantograph. These devices are generally formed of plates of steel with a view to enhancing the strength thereof.
The noise, however, advances around the edge of a wall even so much as to reach the rear of the wall due to the diffraction of sound as mentioned above. When the soundproofing device is installed so as to avoid rising above the windows of electric cars and other vehicles, therefore, the noise readily advances around the edge of the sidewall and reaches the rear thereof. Consequently, the soundproofing device possibly fails to afford sufficient prevention of the noise.
When the soundproofing device is installed at a high position for the purpose of enhancing the soundproofing effect, it may impair the view in proportion to the size of the device, and may possibly prevent the surrounding sights from being clearly viewed by passengers in an electric car or a vehicle.
The enlargement of the whole device entails such problems as requiring increased strength complicating the structure thereof, causing the weight thereof to increase so much as to render the handling thereof difficult, and increasing the cost of materials possibly at a sacrifice of economy.
This invention has been developed as a consequence of repeated efforts in trial and error and improvement concerning soundproofing devices with a view to overcoming the conventional problems. The object of this invention consists in providing an enfolding sound barrier which is highly effective in abating noise as compared with the conventional soundproofing devices, and further providing an inexpensive enfolding sound barrier which is improved in durability and field working and which can secure a generous view of a surrounding sight.
The present invention provides an enfolding sound barrier comprising a sidewall or a transparent sidewall capable of being seen through, an enfolding body constructed in an enfolding shape with a bent member furnished with a plurality of bent parts and attached to the sidewall for application to an express highway or a railroad, or attached to the different sidewall for application to an ordinary road.
In the enfolding sound barrier, the enfolding body is provided in an upper part of a back surface side thereof with a sound-absorbing part disposed in an inclined state. The bent member is provided with a sound-absorbing material fixed onto an outer peripheral surface side of a leading terminal region of the bent member.
In the enfolding sound barrier, the plurality of bent parts of the bent member comprises four bent parts preferably having respective angles of 142, 142, 142 and 142 degrees. The barrier can further comprise a supporting member to which the bent member is integrally fixed to form a further enfolding shape and which is furnished with a bent part having an angle of 173 degrees.
The enfolding sound barrier can further comprise at least one bent member identical with the bent member, and the bent members are piled in two or more stages, one on top of the other, or one on top of another. On the other hand, the enfolding sound barrier can further comprise a leading terminal member, and the bent member, the supporting member and the leading terminal member are each made of an aluminum alloy and formed in a plate shape by a working means including extrusion molding.
In the enfolding sound barrier, the enfolding member has an enfolding region desirably attached so as to be displaced in a direction of increasing a width of an express highway or railroad relative to the sidewall. The different sidewall alternatively may be formed of a resinous material of polycarbonate plastic for application to an ordinary road.